276 Neiv Species of Crinoidea from the 



twice as wide as high, and moderately impressed at the 

 sutures. First radial plates proportionally large, once and 

 a half as wide as high, the superior lateral faces very long. 

 Second radials short, broad, quadrangular. Third radials 

 short, broad, heptagonal, larger than the second radials, 

 obtusely angular above, sujjporting on each upper face a 

 supra-radial plate of medium size ; these support on their 

 outer sides brachial plates, and on their inner sides supra- 

 radials of the second order, giving six arms to each 



ray. 



First interradial plate very large, seven or eight-sided, 

 supporting two smaller plates in the second range ; the 

 plates above are situated between the bases of the arms, 

 and are more properly dome plates. Anal plates undeter- 

 mined. Resting upon the upper truncated sides of the 

 first supra-radial plates, and between the second supra- 

 radials, there is a small pentagonal plate, which is cuneate 

 below, with its surface distinctly grooved longitudinally. 

 Dome composed of moderate sized, polygonal plates, 

 gradually tapering above, and continued in a large pro- 

 boscis. Surface of body plates marked by two sets of ra- 

 diating ridges, those on the summits of the rays and their 

 subdivisions being stronger, highly elevated, and subno- 

 dulose ; the other ridges are less conspicuous, consisting 

 of numerovis striae, radiating from the centres of the 

 plates to the margins, the principal ones meeting at the 

 centre. 



This species is of the type of A. ornatus, (Geol. Rep. 

 Iowa, Part 11. page 583, pi. 10, fig. 12 ; ) but differs in form 

 both of body and dome. 



Geological formation and locality. Burlington lime- 

 stone, Burlington, Iowa. Collection of C. A. White. 



Actinocrinus excerpt us (n. s.). Body depressed, broadly 

 bowl-shaped, base broad, deeply depressed. Basal plates 

 small, concealed beneath the column attachment (except 



